Category: airway

This 9 minute video demonstrates the strengths and weaknesses of an intubation strategy that relies on dissociation with ketamine.

The essential strength, compared to RSI, is that a breathing technique keeps the patient breathing during laryngoscopy, which transforms the procedure from high-adrenaline to highly controlled. You see in this video that my (fabulous) resident was able to take his time, try different blades, slowly advance and adjust while using view optimization techniques as the patient continued to breathe. This is an extremely powerful way to add safety to the riskiest procedure commonly performed in acute care. We would have been able to carry on with his attempts for longer, had we not been inconvenienced by the arrival of a trauma patient.

Keeping the patient breathing during intubation has a long history in emergency medicine, starting with the brutal and often unsuccessful blind nasal intubation, which, fortunately, is now seldom performed. Many of us learned to do operating room style awake intubation, which relies on thorough local anesthesia using atomized/nebulized/topicalized/regionalized lidocaine, so the patient can remain truly awake and breathing during the procedure. Lidocaine-focused awake intubation is a fabulous technique that requires expertise and equipment not available to all acute care providers, but also–depending on your level of skill–time and patient cooperation. Time and cooperation is something we may not have downstairs or on the side of the road,* but what we lack in time and cooperation, we can make up for in ketamine.

When we use dissociative-dose ketamine to do the heavy lifting in allowing the patient to tolerate laryngoscopy, we obviate much of the needed topicalization expertise/supplies, abbreviate the needed time, and add cooperation with ketamine, cooperation in a vial. The patient becomes dissociated, breathing but unconscious, which is why I use the term breathing intubation rather than the much more accepted term awake intubation to describe it.

Many patients who receive dissociative-dose ketamine without a paralytic will have some muscle rigidity, and some will develop laryngospasm (which is glottic muscle rigidity). The patient in this video had some rigidity, which resolved and was not a problem, and this is usually the case. But patients who get ketamine to facilitate laryngoscopy are at much higher risk than procedural sedation patients (who are not having their airway instrumented) to develop laryngospasm and occasionally jaw rigidity, which, together, can cause an immediately dangerous cannot intubate cannot ventilate scenario. Anytime KOBI is being undertaken, a paralytic must be immediately available, ideally drawn up in a syringe, so that the procedure can be converted to a paralyzed technique at any point.

How KOBI fits into our expanding airway toolkit is expertly described by Andrew Merelman and Michael Perlmutter in this WJEM paper.

Postoperative neck hematoma is not often discussed in emergency medicine but behaves a lot like neck trauma, because it is neck trauma. These patients should be managed with a high-resource approach and discharged reluctantly, after careful deliberation.

Laryngoscopy involves a series of unnatural movements and hand-eye skills that are not easily learned while simultaneously caring for a dying patient. The Paper Throat is a low fidelity but high yield direct laryngoscopy training tool that is easily assembled and practiced. The hope is that routine use will generate laryngoscopy muscle memory so that training providers can focus on other aspects of airway management when called upon to intubate IRL.

Saturation continues to drop until 1:46, then recovers from its nadir of 77%

At 1:58, saturation reaches 100% again

Lessons:

1. When the sat is on its way down, the patient is more hypoxic than the pulse ox shows. This is another reason why, when laryngoscopy is not producing an acceptable view of the glottis, you should come out and reestablish ventilation/oxygenation earlier than you think. A more important reason to come out and bag early is described here.

2. When you are reestablishing oxygenation (using a bag mask, laryngeal mask, or endotracheal tube), do not use the pulse ox to judge the adequacy of ventilation, use capnography. That means the capnogram should be attached to the bag mask/LMA/ETT before the first breath is given. If the capnogram is good, ventilation is good, and the pulse ox will catch up, so relax and stop bagging so quickly.

Rapid sequence intubation, the simultaneous administration of a paralytic and induction agent immediately followed by laryngoscopy, provides the optimal view of the glottis and prevents emesis. RSI is the best strategy for most patients who require intubation, but not all.

When you’ve decided to intubate, first maximally preoxygenate. If the patient will not cooperate with your preoxygenation plan, even after you’ve asked nicely, that’s your cue to add cooperation in a vial, ketamine, and then oxygenate, before you push the paralytic and intubate. This is delayed sequence intubation. Otherwise, carry on with preoxygenation, and consider a couple of special situations.

The first is the patient who is about to arrest–obtunded, no blood pressure. Any induction agent will cause sympatholysis which, along with the transition to positive pressure ventilation, may precipitate arrest, so ideally we would avoid both while the patient is in the state of nearly arrested. Resuscitate aggressively with fluids, vasoactive drips and treatment of the underlying problem for as long as you can before intubating. If you must intubate the patient who is obtunded with no blood pressure, the safest way to do it is often without any drugs at all, while the patient continues to breathe. If you have to give meds, dose sedatives low and paralytics high.

The next special situation is the patient who has a severe oxygenation or ventilation deficit. The severe oxygenation deficit patient saturates less than 90% on 100% NIV; the severe ventilation deficit patient is compensating for a severe metabolic acidosis, e.g. DKA with pH 6.7. In patients with a severe oxygenation or ventilation deficit, even a brief period of apnea is very dangerous, and since paralysis is certain to cause apnea, it stands to reason that paralysis may not be the best approach. However, these patients are very ill, so conventional awake technique, which requires time and cooperation, will not work well. If only there were a drug that would immediately render the patient tolerant of laryngoscopy, while ventilation and airway reflexes are preserved.

Ketamine-supported intubation, KSI, is pushing an induction dose of ketamine over 20-30 seconds, then performing laryngoscopy. KSI is awake intubation with minimal or no local anesthesia, or, if you prefer, RSI without paralysis.

By omitting the paralytic, KSI carries a chance of two harms: suboptimal view of the glottis, and emesis/aspiration. I address these harms in detail in this discussion; the advantage in glottic exposure offered by paralysis is less significant in the era of video laryngoscopy, which almost always provides a great view of the cords, and the risk of emesis/aspiration is very small most of the time. In any case, these harms must be weighed against the harm of apnea for the patient in front of you. Others have described a similar strategy, augmenting ketamine with etomidate as necessary.

The last and most important special situation is high concern for difficult laryngoscopy. You assess all your endotracheal tube-requiring patients for difficult laryngoscopy, either intuitively or explicitly, and most of the time, you think, I got this, in which case, carry on with RSI like you always do. But if you think it is likely that laryngoscopy will fail, and the patient is presently benefiting from their own ventilatory efforts, abolishing those efforts with RSI may not be the best choice.

Even in scary laryngoscopy cases, RSI is probably still optimal if the patient is high risk to vomit (has been vomiting, upper GI bleed, bowel obstruction). In these scenarios, the protection against emesis afforded by paralysis is compelling, so proceed with RSI, but use a double setup, with your partner on standby, ready to cut the neck. Keep the head of the bed up and drop an NG tube in beforehand if you can.

The patient whose airway is a lawyer’s dream and isn’t a particular risk to vomit is ideally intubated without a paralytic, while continuing to breathe, awake intubation. Awake intubation has two pharmaceutical arms: local anesthesia, and systemic sedation. The more cooperative the patient and the less urgent the airway, the more you can rely on local anesthesia. So if you have time and cooperation, dose glycopyrrolate or atropine, then generously nebulize, topicalize, and atomize lidocaine, then you can slowly, carefully do your laryngoscopy, or flexible endoscopy, or whatever you want, as the patient is awake and breathing. In the OR, where patients and physicians are stable and cooperative, patients with concerning airways are intubated with minimal or no sedation at all, which affords an enormous margin of procedural safety. Patients being intubated in the ED are of course neither stable nor cooperative, but a similar degree of safety can be achieved using ketamine: the less time and less cooperation, the less lidocaine, the more ketamine.

In the extreme version of the emergency department awake intubation, give induction dose ketamine and go: KSI. Consider KSI for your severe oxygenation/ventilation deficit patients, but also when you are concerned that laryngoscopy is going to fail and the patient won’t cooperate with, or you don’t have time for, a more civilized, operating theater-type awake intubation. Have a paralytic ready in syringe, in case you want to convert to RSI at any point, and incorporate a double setup component to your approach, because your concerns about laryngoscopy might turn out to be well-founded.

Awake intubation is placing an endotracheal tube in the trachea while the patient continues to breathe. The principle advantage over RSI is that you do not take away the patient’s respirations or airway reflexes, which makes the process safer in many circumstances. The disadvantages are that the patient’s personality and movements, as well as the patient’s airway reflexes, must be managed, which takes time, and even when done well, the view you get won’t be as good as in a paralyzed patient. Instrumenting the back of the throat may cause gagging and possibly vomiting, though this is quite unlikely to lead to clinically significant aspiration (because the patient is awake). The more difficult airway features, and the less urgent the intubation, the more likely you should intubate awake. Patients who are at high risk to vomit are not good candidates for an awake technique.

The two arms of awake intubation are local anesthesia and systemic sedation. The more cooperative your patient, the more you can rely on local; perfectly cooperative patients can be intubated awake without any sedation at all. More commonly in the ED, patients will require sedation. Ketamine is the agent of choice in most circumstances, as it sedates without depressing respiration or airway reflexes. In somewhat cooperative patients, 20 mg boluses, titrated to effect, work very well. In very uncooperative/agitated patients, a full dissociative dose (1.5 mg/kg) is an effective strategy though a brief period of apnea is usual if dissociative doses are delivered as a bolus, and laryngospasm is a possible complication. For those patients where raising heart rate or blood pressure is undesirable, benzodiazepine sedation will have a less effective but still salutary effect. Dexmedetomidine is probably a better agent in these scenarios, but is a little tricky to use and not available in most EDs.

Even if using full dissociative dose ketamine, do your best to anesthetize the airway, using the steps listed in the box above, excerpted from the ED intubation checklist. Local is much facilitated by a dry mucosa, so the first step, if possible, is to dry the mucosa with glycopyrolate or atropine, followed by suction and dabbing with gauze. Once this is done, anesthesia is delivered by nebulization, atomization (ideally using a purpose-built atomizer like a MAD device), and drip techniques.

Once the patient is adequately anesthetized/sedated, you gently proceed with your intubation method of choice. When you see the cords, you can pass the tube without paralysis, place the bougie and then paralyze, or paralyze before placing the bougie/tube. I recommend the second option, and I also recommend that you prepare to do a full RSI, with whatever equipment and drugs you would use in an RSI case.

When done well, awake intubation is quite anticlimactic, as the patient simply continues to breathe, and saturation is maintained, for as long as needed. While RSI is terrific and will work very well in most cases, if you perform RSI on a patient who was a good candidate for an awake technique, and it doesn’t go well, you have made a consequential mistake. Awake technique requires little additional skill; it is under-utilized in emergency medicine because it requires what emergency providers often lack: patience. In this case, however, patience is well rewarded.